In 1901 are to be found these two men in Stornoway:
Alexander Maclennan, 60, Guano Factory Labourer, 15 Coll, b. Stornoway
John Mackenzie, 56, Labourer in Guano Factory, 29b Lower Sandwick St, b. Stornoway
I am pretty sure that the word IS ‘Guano’ rather than being ‘Gas’ or ‘Gut’ which (along with ‘Oil) are the only other instances of the word ‘Factory’ that appear in this census for the town. There are less than a dozen Guano workers to be found in the whole of Scotland between 1841-1901 so these two are pretty special.
I understand the term ‘Guano’ to refer not only to the excrement of sea birds, bats and seals but also to manure made from fish and whales. It seems entirely possible that the Guano was produced at the ‘Gut’ Factory but if anyone has any further information regarding the Guano Factory of Stornoway then please do contact me.